1. Field of the Invention
The invention relates to an ink ribbon positioning system, and more particularly, to an ink ribbon positioning system for identifying various positions of a color ink ribbon of a color printer, such as a thermal printer.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a perspective view of a prior art ink ribbon positioning system 10. The ink ribbon positioning system 10 is used for identifying the position of a color ink ribbon 11 of a color printer (not shown). The ink ribbon 11 comprises a plurality of sequentially arranged transparent color frames 14, 16, 18 for storing yellow, magenta, and cyan dyes. The ink ribbon 11 further comprises a plurality of sequentially arranged strip areas 20, 22, 24 separately installed next to each of the color frames 14, 16, 18. The strip area 20 is an opaque area installed between the yellow and cyan color frames 14, 18. The strip area 22 has a top transparent portion and a bottom opaque portion and is installed between the yellow and magenta color frames 14, 16. The strip area 24 also has a top transparent portion and a bottom opaque portion and is installed between the magenta and cyan color frames 16, 18.
The ink ribbon positioning system 10 further comprises two light sources 26, 28 arranged along the way perpendicular to scrolling direction on one side of the ink ribbon 11, and two corresponding sensors 30, 32 installed on another side of the ink ribbon 11. The position of the ink ribbon 11 is identified through the strip areas 20, 22, 24. The detection of the strip area 20 by the sensors 30, 32 corresponds to the beginning of a new yellow color frame 14 of the ink ribbon 11. The detection of the partially opaque area 22 or 24 by the sensors 30, 32 corresponds to the beginning of the magenta or cyan color frame 16, 18 of the ink ribbon 11. Because the ink ribbon positioning system 10 is installed with two sets of light sources 26, 28 and sensors 30, 32 for detecting the position of the ink ribbon 11, it""s production cost is very high. In addition, the light sources 26, 28 must be always on together so that the position of the ink ribbon 11 can be detected by the sensors 30, 32. This makes the system not very flexible.
It is therefore a primary objective of the present invention to provide an ink ribbon positioning system to solve the above mentioned problem.
Briefly, in a preferred embodiment, the present invention provides an ink ribbon positioning system of a color printer for identifying various positions of a color ink ribbon of the color printer. The ink ribbon comprises a plurality of sequentially arranged color frames for storing different color dyes. The color printer comprises a thermal print head for printing the color dyes onto an object and a driving device for scrolling the ink ribbon relative to the thermal print head. The ink ribbon positioning system comprises:
a first light source for emitting a first light beam through the ink ribbon;
a second light source for emitting a second light beam through the ink ribbon;
an optical sensor for detecting the first and second light beams penetrating through the ink ribbon and generating an output voltage; and
an identification device electrically connected to the first and the second light sources;
wherein when the driving device scrolls the ink ribbon relative to the thermal print head, the identification device will control the first and the second light sources and identify the position of each of the color frames of the ink ribbon according to the output voltage generated by the optical sensor.
It is an advantage of the present invention that the ink ribbon positioning system only comprises one optical sensor. Thus, the number of components of the color printer is reduced and the production cost is lowered. In addition, it is not necessary for the light sources to be always on together. This substantially makes the system flexible.
These and other objectives and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.